Decorative and functional coatings or inks for glass, ceramics and other hard surfaces normally range from a rigid solid to a semisolid at room temperature. Normally the products are heated to a temperature in the range of about 120.degree.-270.degree. F. to melt or soften them for application by any one of the standard ink or coating application methods. One preferred method is the use of a heated metal screen and a rubber squeegee in a high temperature version of the "silk screen process". Ceramic inks in thermoplastic carriers are commonly applied in this manner. Following application, the coating is subjected to curing. A critical requirement for a thermoplastic/thermosettable screen ink is that it have a sufficiently wide difference between the melting or softening point--which dictates the screen temperature--and the curing temperature to provide adequate working time on the screen. If that difference is too small, the ink may be unstable on the screen and begin to gel or cure prematurely.
Conversely, if the system is formulated to be so latent that very long cure times and high temperatures are required for curing, the system is impractical for high speed production equipment and/or the thermal stability of the pigments and other additives employed becomes a concern. As employed herein the term "thermoplastic/thermosettable refers to materials which initially melt or soften upon raising the temperature above room temperature and which, upon further raising of the temperature begin to harden or set as a result of curing. By "latency period" is meant the period during which the thermoplastic/thermosettable composition can be maintained at a given temperature before becoming hardened or set.
For coating or ink compositions such as those of this invention, the choice of the curing agent(s) employed is important since the latency period must be, for example, several months at room temperature and up to several hours at temperatures of about 140.degree. to about 270.degree. F. In the present invention, certain specified curing agent(s) are employed.